Process of degumming bast fibers



Patented Aug. 5, 1952 v was UNITED STATES PATENT: OFFICE N Drawing. Application August 22, 1949, Serial No. 111,759

8 Claims. (C1. 8-138) This inventionrelates to a new and improved process for the degumming of bast fibres, such as fiax, hemp'and especially ramie (sometimes called China grass). The principal object of this invention is to provide a simple, economical, and eificient process for the degumming of bast fibres for subsequent use in the textile industry.

An additional object of this invention is to provide a process for the degumming 0f bast fibres which will produce a fibre having better strength characteristics than fibres degummed by previous methods.

Bast fibres, such as ramie, after decortication are generally held together by gums composed of plant starches, sugars and related materials of a pectic nature. These substances are relatively insoluble in 1-120 and unless they are thoroughly removed the yarn is inclined to be wiry and very diffioult to spin into fine yarn. The flex quality of the fibre is particularly affected by the completeness of the degumming. The total gum content of raw ramie fibre varies from 15 to 35 percent with an approximate average of 25%. These adhering gums while relatively insoluble in H2O are soluble in alkaline solutions when heated or subjected to pressure, and in the past, degumming methods using heat and pressure of various sorts have been used to free the fibres from these undesirable substances. Generally speaking, previous methods have used digestion with NaOH or other alkali (with or without added chemicals) at elevated temperatures and frequently under pressure and with vigorous agitation. The significant factors involved in the degumming of ramie fibres are: pH of the degumming solution, temperature, duration of process, extent and method of agitation.

A high pH causes degradation of the cellulose, and if carried on at elevated temperatures the process causes an embrittling of the fibres. Be cause as it penetrates to the center of the mass of fibre the alkali is progressively saturated with the soluble gums, it is necessary to use an amount of caustic too high to avoid some fibre deterioration. Vigorous agitation results in tangled and knotted fibre unsuitable for commercial use. In some processes reducing agents have been used with the alkali in order to prevent the damage to the fibre by action of the NaOH; in others, a subsequent souring process has been necessary. Degumming by bacteriological action has been tried but resulted in fibre considered too Weak and brittle to be satisfactory for textile purposes and is not generally used.

I have now discovered a simple process which produces a fibre possessing superior properties of strength, and which eliminates the objectionable features of past methods, i. e. the high pH, high temperatures. elevated pressure and vigorous agitation. My method consists of simply soaking the fibre in a bath consisting of a combination of a synthetic detergent or wetting agent possessing good emulsifying I and penetrating powers with water, turpentine or alcohol, at room temperature. While neither turpentine nor the alcohol alone liberate the gums, both of these, when emulsified with one of the sulfonated compounds, make an extremely effective degumming solution. The degumming solutions may be of varying composition. I have obtained good results with such penetrants and/or detergents as the sodium salt of an alkylated aryl 'polyether sulfate, known as Triton 770 Concentrate (Rohm and Haas), with Alkanol Bof Du Pont-the sodium salt of an alkyl naphthalene sulfonic acid, with monobutyl biphenyl sodium monosulfonate, and with the alkyl aryl 'sulfonate, known as Detergent 'D-40, produced by Oronite Chemical Company. These sulfonated' penetrants, even though possessing different chemical formulation, providing soaking bath of low pH (either alone or with water, turpentine or higher alcohol) which, by a softening and dissolvingaction on the plant gums enable, them tobe readily removed by squeezing, washing, and rinsing after the soaking period. This soaking process removes virtually all of the gums, leaving the cellulose fibre with all of its natural strength, in excellent condition for subsequent processing of the textile industry.

Although synthetic detergents have been used before in cellulose treatment in bleaching processes as, for example, in U. S. Patent 2,383,900, and 1,983,008, nowhere has there been an indication that degumming of bast fibres could be accomplished by soaking, at room temperature, in a bath consisting of sulfonated wetting agents of the type described either alone, or in conjunction with either alcohol or turpentine. In fact the O. T. S. Ramie Report P1397342 of November 30, 1948, prepared for the Omce of Technical Services of the Department of Commerce showed that tests made with various commercial wetting agents and detergents for degumming produced no results better than the use of sodium polyphosphates with 6% NaOH and NazSOrr and gave no indications of possible use of detergents alone or with turpentine or alcohol.

Example 2 One hundred pounds of raw decorticated undegummed ramie fiber was soaked at room ternperature in a bath consisting of 10 parts H20 and one part dry fibre with 5% Detergent D-40 and 5% turpentine for a period of five hours. The liberated gums were removed by squeezing and washing the fiber.

Example 3 One hundred pounds of raw decorticated unclegummed ramie fiber was soaked at room temperature in a bath consisting of 5 parts water to 5 parts isopropyl alcohol and 5% of Triton 770 Concentrate. The liberated gums were removed by squeezing and washing the fiber.

Example 4 One hundred pounds of raw decorticated, undegummed ramie fiber was soaked at room temperature in a bath consisting of 10 parts turpentine to one partof decorti cated fibre with 5% monobutyl biphenyl s o d i u m monosulfate (Aresket-Monsanto Chemical Co.). Washing and rinsing removed the liberated gums.

Good results were also obtained using Alkonol B, a sodium salt of an alkyl naphthalene sulfonic acid produced by Du Pont. I

In the case of procedures using turpentine in the bath, the turpentine from the squeezed fibre and residual in soak tank may be recovered for re-use by conventional methods of distillation and condensation.

The soaking solutions may be reused after the squeezing process so long'as they have efiicacy. The softened and dissolved gums may be removed either by mechanical squeezing and/or washing, and may be followed by a mild alkaline boil off and bleaching. If desired, the fibers may also be oiled to facilitate spinning. The soaking time depends on the gum content of the fibres, and the combinations and proportions and amounts of the ingredients may be varied without departing from the spirit of the invention. I

What I claim is:

1. The process of degumming bast fibres which consists of soaking the fibres at room temperature and pressure in a solution containing a soluble salt of an alkylated aryl polyether sulfate.

2. The process of degumming bast fibres which consists of soaking the fibres at room temperature and pressure in a solution consisting of an alkylated aryl polyether sulfate, water, and a member of the group consisting of turpentine and alcohol.

3. The process of degumming bast fibres which 7 consists of soaking the fibres at room temperature and pressure in an aqueous solution containing the sodium salt of an alkylated aryl polyether sulfate and turpentine.

4. The process of degumming bast fibres which consists of soaking the fibres at room temperature and pressure in an aqueous solution containing the sodium salt of an alkylated aryl polyether sulfate and isopropyl alcohol.

5. The process of degumming bast fibres which consists of soaking the fibres at room temperature and pressure in an aqueous solution of a sodium salt of an alkylated aryl polyether sulfate. 6. A soaking bath for the degumming of hast fibres at room temperature and pressure which consists of an aqueous solution of an alkylated aryl polyether sulfate and a member of the group consisting of turpentine and alcohol.

7. A soaking bath for the degumming of best fibres at room temperature and pressure comprising the sodium salt of an alkylated aryl polyether sulfate and turpentine.

8. A soaking bath for the degumming of bast fibres at room temperature and pressure comprising the sodium salt of an alkylated aryl polyether sulfate and a higher alcohol.

MAZY BYRNE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. THE PROCESS OF DEGUMMING BAST FIBRES WHICH CONSISTS OF SOAKING THE FIBRES AT ROOM TEMPERATURE AND PRESSURE IN A SOLUTION CONTAINING A SOLUBLE SALT OF AN ALKYLATED ARYL POLYETHER SULFATE. 